Production of methylamine



Patented Sept. 6, "193 2 I UNITED" STATES PATENT OFFICE JEROME mam nu) mom 0. swmmt, or rmr: more, INDIANA, assreuors 'ro comnnacmr. sonvams comm-non, or mama nau'rn, mnuma, aconroaanon or mannnm l 4 PBQDUCIION ornm'mmnm in Drawing, Application fled m 18, 1830. Serial 1%. 488,998.

This invention relates to a process forpro the reaction. The latter point is ofparticuducing methyl amine from ammonia and lar mportance due to the difliculty in sepmethanol. It relates particularly to a procaratmg and recovering the difierent amines ess whereby high conversions ofthe reactand to the uses to whlch the different amines 5 ants and good yields 'of monomethyl-amine may be applied. Extensive investigations 55 are bt i d, I have shown that up to the .present .time it is In the past methyl amine'has been. #prenot possible to react ammonia and methanol pared synthetically by a-number of difierent and obtain only the monomethyl amine as methods, among which is the process of ush s b n cl ime y prior r A rdmg ammonia and methanol as the reactants. ing. to the present invention, however, it is my 'Sabatier and Maihle (Compt. rend. 148, 898 shown that the ratiosof the different methyl (1909)) reported thatvarious alcoholsreamines found by the reaction between am act with ammonia when the vapors are passed moma and methanol may be regulated withover thorium oxide or blue tungstic oxide m certain deternuned limits by careful re at 350370 (3., waterbeing limi ted and lation ofsuch factors as catalyst, rate of ow 65 th ri a d Secondary nd ome ten- -of reactants, temperature, ratio of ammonia I tiary amine formed, but these investi ators o m thanol, etc. I I did not. actually use ethanol. Smo enski Ith 1 n found h t m mmal? Such (Rocz. Chem. 1921', 15232-43). stated that as aluminium silicate either pure or in the when the vapors of methyl, ethyl, or amyl form of naturall occurring clays hke blue alcohol react with ammonia in the presence clay, doucil, Putnam play?,Indianaite, of a dehydrating catalyst such as alumina at feldspar, crushed building tile, etc. may be about 300 0., a satisfactory yield of primary, satisfactorily used as catalysts for the producsecondary, and tertiary iaminesiis obtained, tion of -methyl amine from ammonia and but that secondary products such as olefines methanol. v 75 and ethersare obtained. Davis and .Elder- In selecting a catalyst for industrial use it field (J. Am. Chem. Soc. 50, (1928), 17 86) is necessary to consider such factors as availreported that methyl amine is ormed when ability, initial cost, physical structure, chemimethanol and ammonia are'pa'ss'ed over a cal composition, necessity of subjecting magahot thorium oxide catalyst, the best tem era-. terial to preliminary purification or other ture appearing to be -325-330 C. an the treatment before it can be satisfactorily used best relative concentration about 0.80-0.83 -asa catalyst, duration of life of the catalyst,- mol of ammonia per mol of methanol. These possibility and ease of reactivation, catalysis investigators reported that under the best of undesirable side-reactions; etc. Catalysts.

I conditions nearly one-third of the methanol such as those'which have just been enumer- 85 I is converted into methyl amine. They also ated meet these requirementsina most satisstated that no secondary or tertiary amines factory manner. vClayscontaining aluminiwere. produced. This statement as well as umsilicate are among the most. widely disthe y elds reported by these investigators tributed substances in nature and are hence are believed to'be inaccurate and misl'eadboth easily obtainableandcheap.- In fat, g9 ing due to the unsatisfactory methods of they can be obtained so cheapl yfthat the fac 5 analysis used by them. .1. V, tors of. reactivation and durationof life of- I In determining the value. of a process for the, catalyst become'of comparatively little the production of methyl amine on a com-'- importance. They also give ood convermercial scale it is necessaryto consider sevsions of the reactments and att e same time '9 l eral important points, for example, the rate do not unduly catalyze i1 desirable side of conversion of the ammonia andmethanol, reactions. y the extent of side reactions giving products v The procedure-by which methyl amine is other than methyl amine, and the ratios of obtained according to the present invention F the different methyl amines formed during may be illustrated as followse-Theoperm tion' consists broadly in admitting ammonia gas and methanol to -a vaporizer heated by suitable means. The temperature required at this point may, for example, be maintained by heatm the'vaporizer by means of the vapors of boilmg butanol or other liquid of suitable,

rate the methyl amine from the unconverted ammonia, methanol, water and any by-products, which may be formed during the reaction. Any suitable method of recovery. may be employed, as for example, the gases leaving therreaction vessel may concentrated hydrochloric acid, and the resulting amine hydrochlorides separated and the desired am nes obtained. Or, if referred, the 'amines'may be separated an recovered by fractional distillation under ressure according to the procedure outlin in a co-pending application.-

Results showing the use of aluminium silicate and clays as catalysts under varying conditions are shown in the following table.

Table I h I Mon T M1-NH' Space Oonv. 3min: 0am 916p 1 N'iir mil 1 Mols MeOH ,oclw i p 95 a Indiaualte. 450 1.51 140 so a maximum... 400 0.50 100 00 I a (I3ndian.:gt; fi 400- 1.00 100 a Ht-138 c o tt-izzzxz; 1 31:3 gga: 0 edspar r 40o zoo 100 a 50-00. a $22322.-." no zoo 1am in as The composition 0 the above catalystsis shown in Table2 wh1 h follows:

. a l Tabla? (a) Indianaite See Mellor-Comprehensive Treatise on Inorganic and Theoretical Chemistry (l924),vol. 6, p. 495'. '(b) Blueclay' Alumina 26. 85. Silica 55. 22

. mo. r 1, 06-

n 0, 15 P206 f o .Wfiter 6. 42

be absorbed in' 1 the range about 400 C.

30-40%, but the gortion of monbmet (6) Crushed buildin tile 4 Prepared from lue clay by crushing,

grinding and igniting at 2000 F.

(a) fDoucil Mellor Ibid yol fi, p. 570'.

(c) (Feldspar) Mellor Ibid vol. 6, p. 661.

(d) Putnam clay- Silica 45. 39 Alumina; 39. I9 F6203 0. (16111;) 2. 15

0. 29 Alkalies' 0.83 Water 14.01

' Consideration of data obtainedby operatmg under various conditions indicate that the final results obtained are regulated by the catalyst, the temperature at which the reaction is carried out, theratio of the amount of ammonia to the amountof methanol passed over the catalyst, the space velocity of the gaseous mixture being reacted, as well as certain otherfactors to ,be discussed below. By the term space velocit as used above,

is meant the number of on ic centimeters of reacting gases per cubic centimeter of cata-. lyst passed over the latter per hour.

Variations of the factors above enumerated generally lead to changes in both the rates .of conversion of the raw materials and in the ratio of monomethyl to the secondary and tertiary methyl amines, and hence these factors may be varied within method of operation and recovery 0 the prod ucts may require.

300 C. to about 500 C. For most purposes, however, it i's'preferable to 0 erate within 350 -450 0., and etter' still at The ratio of ammonia to'metlianol is to-a very large extent determined b the method of operation and the economy 0 recovering the products formed during the reaction. By using a' gas mixture consisisinglof say six parts of ammonia to one-part of methanol approximately of the methyl amine formed will bethe monomethyl amine, but only approximately 7 of the ammonia will be converted, thus necessitating greatly certain limits as difierent products are desired .or as the 1particular- 1 For example, the tempera ture of the catalyst may be varied from about increased expense inrecovering the unused portions of the raw.

material. On the other"hand, assuming that thenother factors are left the same,.1f the gas mixture contains only. about one part of ammonia to one part of methanol, the monomethyl. amine content of the methyl amine formed will be reduced to approximately I conversion of the ammonia to methyl amine will be increased to approximately 35-40%. r-By decreasing the'ratio of ammonia to methanol still further, the proyl amine will be further ecrea'sed. In order, therefore, to obtain as about the most satisfactory results under general operating conditions.

The space velocity of the reacting gases may be varied'from to about 3500. The conversion at 500 is equal to that at 100, other conditions being the same. Above 1100 space velocity the conversion appears to begin to decrease.

The operating conditions and particularly the temperature employed depend to some extent also upon the catalytic effect of the metals from which the catalytic apparatus is constructed. Aluminium silicate and clay catalysts do not crack methanol at 400 C. but do begin to show some cracking above 425 C. When, however, the heated catalyst container is constructed of cast iron or cold rolled steel the cracking of the methanol is accelerated appreciably. On the other hand, when copper metal is employed there appears not only to be no increase in the cracking of the methanol at a given temperature, but there even appears to be a slight decrease in the tendency for this undesired reaction to take place. From a consideration of these factors, therefore, it is apparent that more satisfactory results are obtainable when the heated surfaces of the apparatus with which 1 the reacting gases come into contact are constructed of copper metal rather than of iron or steel.

What is claimed is:

1. Process for the production of methyl amine which comprises passing a mixture of methanol and ammonia at temperatures ranging from 300 to 500 C. over catalysts comprlslng aluminium silicate, and recovering and separating the products thereby formed.

2. Process for the production of methyl amine which comprisespassing a mixture of v methanol and ammonia at approximately 400 C. over catalysts comprising aluminium silicate, and recovering and separating the products thereby formed.

3. Process for the production of methyl -amine. which comprises passing a gaseous mixture comprising one part methanol and one to six partsammonia at temperatures ranglng from 300 to 500 C. over catalysts comprising aluminium silicate, and recovering and separating the products thereby formed. j

4. Process for the production of methyl amine which comprises passing a mixture of methanol and ammonia at temperatures rangmg from 300 to 500 C. and at space velocities ranging from 50 to 3500 over catalysts comprlsmgf'aluminium silicate, and recovering and separating the products thereby formed. j

'5. Process for the production of methyl amine which comprises passing a gaseous mixture comprising one part methanol and one to six parts ammonia at about 400 C. over catalysts comprising aluminium silicate, and recovering and separating the products thereby formed.

6. Process for the production of methyl amine which comprises passing a gaseous mixture comprising one part methanol and one to six parts ammoniaat about 400 C. and at a spacevelocity of about 1100 over catalysts comprising aluminium silicate and recovering and separating the products thereby formed. v v v 7. In a process for the production of methyl amine, the steps which comprise passing a mixture of methanol and ammonia at temperatures ranging from 300 to 500 C. over catalysts comprising aluminium silicate. 8. In a process for the production of methyl amine, the steps which comprise passing a mixture of methanoland ammonia at temperatures ranging from 300 to 500 C. and at space velocities ranging from 50 to 3500 over catalysts comprising aluminium silicate.

9. In a process forthe production of methyl amine, the steps which comprise passing a mixture of methanol and ammonia at about 400 C. and at a space velocity of about 1100 -methyl amine, the steps which comprise passing a mixture of methanol and ammonia at temperatures ranging from 3009 to 500 C. over catalysts comprising a clay. 1 p 11. In a process for the production of methyl amine, the steps which comprise passing a mixture of methanol and ammonia at temperatures ranging from 300. to 500 C. and at space velocities ranging from 50 to 3500 over catalysts comprising a clay.

12. In a process for the production of methyl amine, the steps which comprise passing methanol and a molecular excess of ammonia at temperatures ranging from 300 to 500 C. and at space velocities ranging from 50 to 3500 over catalysts comprising a clay.

13. In a process for the production of monomethyl amine, the steps which comprise passing methanol and a molecular excess of ammonia at temperatures ranging from 300 to 500 C. and at space velocities ranging fi'om 50 to 3500 over catalysts comprising a c ay. a

In testimony whereof we aflix our signatures. V

JEROME MARTIN. LLOYD O. SWALLEN 

